With the growth of telecommunications, an increasing number of terminal equipments are being called upon to exchange data message streams. These terminals often belong to distinct communications networks. In each of these communications networks, the network resource manager, for example a telecommunications operator, defines management parameter values to be applied to the different data message streams transmitted across the network. Each of these data message streams corresponds to a service such as an Internet service, a Voice over IP (VoIP) service, or audiovisual services such as IPTV services, for example. These management parameter values are the class of service or Differentiated Services Code Point (DSCP), and the priority to be given to the data message as a function of the class of service, for example. The management parameter values are contained in header fields of the data messages.
The resource manager of each of the networks passed through checks that the data streams receive the benefit of the resources necessary to provide the corresponding service. Accordingly, for the same data stream, and thus the same service, depending on whether the data messages are sent from a first network to a second network or vice-versa, different management parameter values are applied to them because the managers are different.
Referring to FIG. 1, a data stream S represented in dashed line in the figure is transmitted between a first terminal T1 and an equipment T2. The terminal T1 belongs to a first communications network R1, for example a home or business local area network, and the equipment T2 belongs to a communications network R2 of the wide area network (WAN) type managed by a telecommunications operator. An equipment E provides an interface between the local area network R1 and the network R2.
If the first network R1 is a home local area network, the equipment E is a home gateway. In this situation the equipment manages the resources within the local area network R1 and the resources to be assigned to the data streams sent from the network R1 to the network R2. As a function of the class of service, the equipment E applies a priority to the data messages sent from the local area network R1 to the network R2 in the event of congestion in order to implement different processing policies for the data streams and thereby to ensure a satisfactory quality of service. The management parameter values are introduced into the headers of the data messages by the terminal T1 itself. However, since the terminal T1 is not necessarily controlled by the operator managing the network R2, the values of the management parameter values contained in the headers of the data messages sent by the terminal T1 are not reliable for the network R2. It is possible for a terminal of the local area network R1 to introduce into the headers of the data messages erroneous or malicious management parameter values. Such erroneous or malicious marking of the data messages leads to incorrect processing of the data messages with the consequences of the appearance of congestion in the different networks and degraded quality of service for all users.
To remove that drawback, a first solution uses the IP (Internet Protocol) address of the equipment T2, which is reliable because it is assigned by the telecommunications operator managing the network R2, in order to have access to the class of service to be assigned to the data messages sent by the terminal T1. However, if that IP address is modified in the event of modifying the architecture or the addressing scheme of the network, the information relating to the class of service is lost. Moreover, the same terminal T1 may wish to use in succession a plurality of different services and therefore a plurality of different classes of service. Determining the class of service from the address of the terminal T1 is thus not always a satisfactory solution.
There is therefore a need for a technique that is free of such drawbacks and that makes it possible, for each data message sent to another network by an unreliable communications network to determine QoS management parameter values to be applied to these data messages, where an “unreliable” network is one that is not managed by a telecommunications operator, such as a business local area network or a home network.